Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already cover safety (readOnlyHint, destructiveHint=false) and determinism (idempotentHint), but the description adds genuinely useful context beyond them: it is free, makes no network request, and returns identical output every time. That reassures an agent this is a zero-cost reference lookup rather than a live check.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

A single dense sentence, front-loaded with what it returns and closing with the relationship to access_check_url. Every clause carries information, though the sentence is long enough that a second short line about its static nature would read cleaner.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

With no parameters and no output schema, the description still enumerates the return contents (five verdicts, meanings, next moves, confidence bases) and the cost/determinism profile. Nothing an agent needs to call it correctly is missing.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

The tool takes zero parameters, so the baseline of 4 applies. There is nothing for the description to disambiguate, and it correctly implies a parameterless lookup.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb (returns/explains) and resource (the five verdicts access_check_url can give, their meanings, next moves, confidence bases). It explicitly positions itself as the companion to access_check_url, so an agent can distinguish it from both siblings without opening a schema.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

Gives a clear triggering context: 'for an agent that has just been refused' and 'the key to reading access_check_url results.' That routes usage well, though it never states when not to call it or names a competing alternative beyond the implicit pairing with access_check_url.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.